Senate Budget Committee Chairman Kent Conrad warned Tuesday that significant “adjustments” are needed in the White House’s spending plans and said he will oppose any effort to employ special deficit-reduction procedures to expedite the administration’s health care and climate-change initiatives.

The North Dakota Democrat said he is committed to helping President Barack Obama on both fronts. But his comments reflect the steep climb ahead for the new administration as the House and Senate Budget Committees prepare to take up Obama’s proposals next week.

New economic estimates this week from the Congressional Budget Office are expected to aggravate the deficit picture already facing lawmakers, especially for 2009. “I’m expecting significant change. It is going to require adjustments,” Conrad said after seeing some of the preliminary numbers. “I think all of us have a very good sense that they will be more adverse.”

Unlike Obama, who presented a 10-year spending plan, the chairman said he will confine his resolution to just five. Conrad said he made this decision because of the uncertainty of long-range forecasts, but the end result of narrowing the window is significant in itself.

First, it will very likely shrink the $634 billion reserve fund envisioned by Obama as a 10-year down payment for health care reform. Second, it opens Conrad himself to criticism for ducking the long-range deficit problems facing Obama and a national debt that hit $11 trillion this week and could double in the next decade.

“Here’s the God’s truth. We are on a course that, under any construct, ... is absolutely unsustainable,” Conrad said. But his ranking member, Sen. Judd Gregg (R-N.H.), said that shortening the plan was only an “ostrich, head-in-the ground” approach to the problems in the second five years.

“We have to give some confidence to the American people, and the international investment community, that we are facing the debt problem,” Gregg told POLITICO. “Ten-year forecasts are very much a guess, but we know the policies are not going to improve the situation.”

Beyond the ever-changing numbers, Democrats are divided among themselves over how far to go in harnessing the Senate’s special budget procedures to expedite the president’s legislative agenda.

Former President George W. Bush famously used budget “reconciliation” procedures in 2001 and 2003 to push through his tax cuts, and since taking power this year, Democrats have toyed with doing the same as a way to overcome Republican filibuster threats in the Senate. White House Budget Director Peter Orszag has said only that he wants to reserve this option. But Republicans fear that White House chief of staff Rahm Emanuel, a hard-fisted Chicago veteran of the House, is prepared to employ reconciliation if needed to advance the president’s agenda.

In a speech on the Senate floor Tuesday, Gregg seemed to give life to these fears. “You’re talking about running over the minority, putting them in cement and throwing them in the Chicago River,” Gregg said. Asked later if he was alluding to Emanuel, he laughed and asked, “What makes you think that?”

In fact, there are real differences among Democrats, many of whom condemned Bush’s tactics as an abuse of power. In the case of health care, Senate Finance Committee Chairman Max Baucus (D-Mont.) told POLITICO that Obama will get a “better health care reform” product by not going through reconciliation. And Democrats from coal and auto industry states are already lining up in opposition to using reconciliation in the climate change fight.

Conrad’s comments must be seen in this context, but he also is the single most crucial player as the person who will write the resolution brought to the Senate floor.

“Reconciliation was written for deficit reduction. These initiatives are primarily not deficit reduction,” he said of the president’s proposals. And he warned that if the administration follows that route, it will end up with bills that look more like “Swiss cheese” at the end.

The chairman made his comments after meeting Tuesday with Senate Majority Leader Harry Reid (D-Nev.) on the path ahead. Earlier in the day, Conrad and House Budget Committee Chairman John M. Spratt Jr. (D-S.C.) met with Obama himself at the White House.

The president was upbeat later, pushing back against his critics who argue that he is trying to do too much at once.

“The American people don’t have the luxury of just focusing on Wall Street,” Obama said. “They don’t have the luxury of choosing to pay their mortgage or their medical bills. They don’t get to pick between paying their kids’ college tuition or saving enough money for retirement. They have to do all these things.”

Looking ahead, the president said those who oppose his plan must be prepared to come up with answers of their own. “‘Just say no’ is the right advice to give your teenagers about drugs,” Obama said. “It is not an acceptable response to whatever economic policy is proposed by the other party. The American people sent us here to get things done.”